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  • Chainlike silicon nanowires: Morphology, electronic structure and luminescence studies

    • 摘要:

    • 作者:

      Xuhui Sun    Ningbew Wong    Li    李述汤     Tsunkong Sham   

    • 刊名:

      Journal of Applied Physics

    • 在线出版时间:

      2004

  • Visualization of diamond nucleation and growth from energetic species

    • 摘要:

    • 作者:

      Yeshayahu Lifshitz    Meng    李述汤     Akhveldiany R.    Hoffman A.   

    • 刊名:

      Physical Review Letters

    • 在线出版时间:

      2004

  • Lasing in ZnS nanowires grown on anodic aluminum oxide templates

    • 摘要:

    • 作者:

      Ding J. X.    Juan antonio Zapien    Chen W. W.    Yeshayahu Lifshitz    李述汤     Meng   

    • 刊名:

      Applied Physics Letters

    • 在线出版时间:

      2004

  • Electrical transport and electronic delocalization of small fullerenes

    • 摘要:

      We report the electrical transport properties of several small fullerenes sandwiched between two metallic electrodes and modulated by a gate electrode, calculated using an orthodox theory. The relationship between the charging energies and the structures of fullerenes is obtained. Bond types and molecular curvatures are observed to be important in determining charging energies. The calculated current-voltage and conductance characteristics are related to the electronic structures of fullerenes near energy gaps and are adjustable by the applied gate voltages, indicating that molecular devices with different functions can be designed by selecting fullerenes with proper bond types and curvatures, and by changing the applied gate voltages.

    • 作者:

      Ruiqin Zhang    Yanquan Feng    李述汤     白春礼   

    • 刊名:

      Journal of Physical Chemistry B

    • 在线出版时间:

      2004

  • High-quality CdS nanoribbons with lasing cavity

    • 摘要:

      High-density and high-quality CdS nanoribbons were synthesized by a thermal evaporation process. The nanoribbons were characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, and photoluminescence spectroscopy. CdS nanoribbons were found to be single crystals of high phase purity and low defect density. Lasing was observed in the CdS nanoribbons upon optical pumping. The growth of CdS nanoribbons was explained by the vapor-liquid-solid mechanism. © 2004 American Institute of Physics.

    • 作者:

      Yingkai Liu    Juan antonio Zapien    Geng C. Y.    Yueyue Shan    Lee C.    Yeshayahu Lifshitz    李述汤    

    • 刊名:

      Applied Physics Letters

    • 在线出版时间:

      2004

  • An international round-robin experiment to evaluate the consistency of nanoindentation hardness measurements of thin films

    • 摘要:

      We conducted an international round-robin experiment to determine the consistency of nanoindentation hardness measurements of thin films among six different laboratories, using three different samples. These samples were chosen to present a challenge of indenting at small loads (μN range). They were: 250-nm-thick TiN, 700-nm-thick TiC, and 500-nm-thick TiB/TiC multilayer coatings (each layer being 3-nm thick), prepared at Northwestern University using magnetron sputtering on silicon (0 0 1) substrates. Each research team was free to use whatever nanoindentor and analysis methods at its disposal. This round-robin experiment demonstrates that for the hardness range of interest (15-35 GPa) and using well-documented procedures and analysis methods, the reported results from all laboratories are essentially the same, allowing for a statistical spread of approximately ± 14%. For consistent hardness measurements, four precautions must be observed: (i) proper tip-area function calibration, (ii) using sharp indenters, (iii) performing nanoindentation measurements with minimal thermal drift and with drift correction, (iv) using smooth samples, and (v) measuring the full hardness-maximum penetration curve. © 2002 Elsevier Science B.V. All rights reserved.

    • 作者:

      Lee Kitty W.    Yip wall Chung    Chityiu Chan    Bello I.    李述汤     Karimi Ayatollah    Patscheider Jörg    Delplancke    Yang Dehua    Boyce    Buchheit   

    • 刊名:

      Surface and Coatings Technology

    • 在线出版时间:

      2003

  • FTIR spectroscopic studies of the stabilities and reactivities of hydrogen-terminated surfaces of silicon nanowires

    • 摘要:

      Attenuated total reflection Fourier transform infrared (FTIR) spectroscopy was used to characterize the surface species on oxide-free silicon nanowires (SiNWs) after etching with aqueous HF solution. The HF-etched SiNW surfaces were found to be hydrogen-terminated; in particular, three types of silicon hydride species, the monohydride (SiH), the dihydride (SiH), and the trihydride (SiH), had been observed. The thermal stability of the hydrogen-passivated surfaces of SiNWs was investigated by measuring the FTIR spectra after annealing at different elevated temperatures. It was found that hydrogen desorption of the trihydrides occurred at ∼550 K, and that of the dihydrides occurred at ∼650 K. At or above 750 K, all silicon hydride species began to desorb from the surfaces of the SiNWs. At around 850 K, the SiNW surfaces were free of silicon hydride species. The stabilities and reactivities of HF-etched SiNWs in air and water were also studied. The hydrogen-passivated surfaces of SiNWs showed good stability in air (under ambient conditions) but relatively poor stability in water. The stabilities and reactivities of the SiNWs are also compared with those of silicon wafers.

    • 作者:

      Xuhui Sun    王穗东    Ningbew Wong    Ma Dorothy Duo Duo    李述汤     Boon keng Teo   

    • 刊名:

      Inorganic Chemistry

    • 在线出版时间:

      2003

  • Erratum: 'Silicon nanotubes: Why not?' (Chemical Physics Letters (2002) vol. 364 (251) S0009261402013349)

    • 摘要:

    • 作者:

      Ruiqin Zhang    李述汤     Law Chi Kin    Waikee Li    Boon keng Teo   

    • 刊名:

      Chemical Physics Letters

    • 在线出版时间:

      2003

  • Efficient CsF/Yb/Ag cathodes for organic light-emitting devices

    • 摘要:

    • 作者:

      Mei yee Chan    Shiulun Lai    冯敏强    Tong S. W.    Lee C.    李述汤    

    • 刊名:

      Applied Physics Letters

    • 在线出版时间:

      2003

  • Fabrication and characterization of pure and well-aligned carbon nanotubes using methane/nitrogen-ammonia plasma

    • 摘要:

      Well-aligned multiwalled carbon nanotubes (CNTs) were grown by microwave plasma-enhanced chemical vapor deposition using N and NH as the carrier gases and CH as the carbon source. Iron films with 1-5 nm thickness on silicon substrates acted as catalysts. Scanning electron microscopy revealed that the CNTs grew via the base growth mechanism at a rate ∼100 nm/s. Transmission electron microscopy showed that multiwalled CNTs had a "bamboo" structure, and the smallest CNTs of ∼6 nm in diameter were acquired on 1 nm Fe film. These "smallest" CNTs were comprised of amorphous structure, due to the formation of sp C-H bonds as proven by Fourier transform infrared spectroscopy and electron energy loss spectroscopy, suggesting hydrogen incorporation during growth of CNTs. Without N gas, no CNTs could be grown, while curly CNTs with poor alignment were grown with no NH. In both cases, high-purity CNTs with no CN impurities were obtained. Field electron emission revealed that the lowest turn-on and threshold fields were obtained from the CNTs grown on the 1 nm thick iron films on silicon substrate, i.e., 3.5 V/μm and 4.5 V/μm, respectively. Under an applied field of 7.5 V/μm, emission current density of 0.63 A/cm can be obtained.

    • 作者:

      Wong W. K.    Li    Frederick wing fai Au    冯敏强    Xuhui Sun    Lee C.    李述汤     Zhu W.   

    • 刊名:

      Journal of Physical Chemistry B

    • 在线出版时间:

      2003

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